I agree with you on this 1,000%. The only parallel I can think of in recent history is Google's seemingly 15 different messaging apps. And learning all of the weird rules you've described reminds me of programming CSS to take account of IE6 quirks. There's no rhyme or reason.

It makes no sense, and every time they add a new paradigm it just makes it worse. I had high hopes that Stage Manager would finally solve it, but I turned it off after a week. It was just more of the same nonsense.